CVE-2026-90279 in Linux
Riassunto
di MITRE • 17/09/2026
In the Linux kernel, the following vulnerability has been resolved:
md/raid5: round bitmap stripes with sector division
raid5_bitmap_sector_map() aligns the array range to full RAID5 stripe widths before converting it to component sectors. That width is chunk_sectors multiplied by the number of data disks, and it is not always a power of two.
Reproduce with a 4-disk RAID5, 1024-sector chunks, and three data disks. The full-stripe width is 3072 sectors. For a one-sector write at array sector 3072, correct rounding gives array range [3072, 6144), which maps
to component range [1024, 2048). The old round_down()/round_up() logic
instead gives [1024, 4096), which maps to [0, 1024).
Use sector_div() based arithmetic so the rounded range is aligned to the actual RAID5 stripe width.
The deterministic mapper test now reports the fixed component range as [1024, 2048), while the old mask-based range was [0, 1024).
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